Magnetic compass.



F. 0. CREAGH-OSBORNE & A. J. HUGHES.

MAGNETIC COMPASS.

APPLICATION FlLED JUNE 22. ms.

Patented Feb.'20,1917.-

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F. 0. CREAGH-OS BORNE & A. 1. HUGHES.

' MAGNETIC COMPASS.

APPLICATION FILED JUNE 2% I915- I 1,216,953. Patented Feb. 20, 1917.

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MAGNETIC COMPASS APPLICATION FILED JUNE 22, 1915. 1,216,953. Patented Feb.20,1917.

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MAGNETIC COMPASS.

APPLICATION FILED JUNE 22. 1915.

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UNITED STATES PATENT OFFICE.

FRANK OSBORNE CREAGH-OSBORNE, 0F. HORSELL, WOKING, AND ARTHUR JOSEPH HUGHES, OF LONDON, ENGLAND.

' MAGNETIC COMPASS.

Specification of Letters Patent.

To all whom it may concern:

Be it known that we, FRANK Os- BoRNE CREAeH-OsBoRNE and ARTHUR JOSEPH HUGHES, both subjects of the King of Great Britain, and residing, respectively, at Horsell, Woking, in the county of Surrey, England. and 59 Fenchurch street, in the city of London, England, have invented a new and useful Improvement in Magnetic Compasses, of which the following is a specification.

This invention relates to magnetic compasses employed on air-craft and for naval and military purposes, and the invention consists in an improved construction of compass of the floating card type whereby greater steadiness of the card is obtained and which card is, moreover, capable of being read at night without'the aid of artificial light. A further feature of the improved construction of compass is the provision of a lubbers line which is also capable of being read at night without the aid of artificial light.

In a compass constructed according to this invention the compass card is composed of mica or other suitable material having its upper face covered preferably with a collodion film on which are outlined the compass points, divisions and figures. All these points, divisions and figures are painted with luminous radium compound, so that all the points are clearly visible by day or night. Instead of a covering of collodion the card may be covered with a suitable base paint on which all the'points of the compass are marked with luminous radium compound. The card is mounted upon the rim of a circular float which is hollow and has its central portion raised in the form of a dome. Within the float are mounted the magnets or needles of which there may be two or four, and in the center of the float and projecting downwardly from the crown of the dome is an iridium-pointed pivot-pin. This pivot-pin rests upon a hard precious stone, such as a sapphire, mounted in the upper end of a vertical support projecting from the floor of the compass bowl. In the Patented Feb. 20, 191 '7.

compass bowl is mounted a lubbers line consisting of a metal arrow-point which is painted with luminous radium paint, or the lubbers line may be etched in the glass cover and filled in with luminous radium compound.

In the accompanying drawings, which are illustrative of ourinvention,

Figure 1 is a View in vertical section of a magnetic compass more particularly for use on aeronautical machines, and Fig. 2 is a plan View of the compass.

Fig. 3 is a side elevation partly in section, of a compass for use with artillery on land, and the direction of fire from aircraft, and Fig. 4 is a plan view of the compass.

Fig. 5 is a sectional view of a compass for use when marching.

Fig. 6 is a plan View of the compass with the cover closed down, and

Fig. 7 is a View similar to Fig. 6 with the cover removed.

Referring to Figs. 1 and 2 the compass card 1 is mounted upon a circular float 2 which is hollow and is formed centrally with a dome 3 while within the float are mounted twomagnets or needles 4 disposed one on each side of the dome. The compass card 1 is annular in form andis composed of mica with the upper face covered with a collodion film whereon are outlined allthe points of the compass, the divisions and figures, these markings being produced by photographic means. All the markings are then painted with luminous radium paint so that they are visible 'at night without the aid of artificial light. The float 2 with its compass card 1 is suspended by means of an iridiumpointed pivot-pin 5 which is mounted within the dome 3 and is supported upon a sapphire 6 mounted in an upright 7 projecting fromthe floor 8 of the compass bowl 9. Within the compass-bowl is fixed a metal lubbers line or steering mark comprising an upper metal arrow point 10 a lower metal arrow point 11 and a metal strip 12 which serves to secure the outer ends of the arrow points rigid with the compass bowl. The

- modified for use with artille upper arrow point 10 projects slightly over the edge of the compass card '1 while the lower arrow point 11 is disposed approximately in the plane of the compass card.

The compass bowl is constructed in the usual manner with a glass cover '13, an expansion chamber 14, which is charged with the liquid with which the compass bowl is filled, and with a receptacle 15 to receive a lamp 16 if desired. The compass bowl is supported by means of lateral extensions 17 in an outer casing 18 which is mounted upon a suitable base 19. To facilitate the reading of the compass card 1 a lens 20 is provided pivotally mounted between arms 21 extending upwardly from the rim of the compass bowl 9. The lens is furnished with a hood 22 and is readily adjustable as required by the observer to any convenient angle for reading the bearings. In place of the lens a prism may be employed i preferred, such, for instance, as is shown at 29 in Fig. 3.

Figs. 3 and 4 illustrate a magnetic compass which is constructed in a similar manner-to that illustrated in Figs. 1 and 2 but on landand for directing fire from aircra the compass being much smaller than that required for aeronautical pur oses. In this modified construction the lu bbers line 23 is mounted upon the rim of the compass bowl 24 and beneath the glass cover 25, and is painted with luminous radium paint. Around the cover of the compass bowl is a ring 26 furnished with pins 27 which work in a groove formed in the ring 28. whereby the glass cover is held in position. The ring 26 is movable about the ring 28 and is furnished with a prism 29 mounted in a holder 30 pivotally mounted. upon said ring 26. The bearing of an object is obtained by adjustingthe prism 29 toward the object, which may be sighted through a \l-shaped notch 31 formed in the holder 30. The compass bowl 24 is filled with liquid through an inlet 32 and the compasscard 1 has all the points of the compass marked thereon with luminous radium aint so that they are visible at night. For olding the instrument a thumb-lug 24 is provided on the compass bowl.

For use when marching, the construction of the compass is modified as illustrated in Figs. 5, 6 and 7. In this case the construction is similar to that employed for artillery purposes, the lubbers line 23 being mounted upon the rim of the compass bowl 24 or it may be etched in the glass cover 25 and the etched portion filled in with luminous radium paint. A lens 33 is provided mounted in a lid 34 which is pivotallymounted upon a ring 35 working in a groove 36 formed in the rim of the compass bowl 24. The ring 35 is also provided with a pivoted arm 37 which is marked on its inner face with a longitudinal line painted with luminous radium paint. The p1vot'of the arm 37 is opposite to the pivot of the lid 34 so that when these .two members are turned back the'lens 33 is line upon the arm 37, thus enabling the observer to ascertain with great facility and accuracy the bearing of an object.

We are aware that it has been proposed to paint compasses, or parts thereof, with chea luminous paint for the purpose of readlng same in the dark; but these paints depend upon the absorption of the solar rays, and they fail to operate when the compass is kept closed up and in the dark, and operate but poorly in stormy weather. The radium compound used in the luminous radium paint hereinbefore referred to does not depend upon any outside influences, but upon the radio activity for its luminosity, and this luminosity lasts indefinitely, no matter whether the compass is kept in the dark or not. y

We are aware that it has been proposed to mark a compass. card with ordmary luminous paint, but such paint is not of practical use in cases where the compass has to be read at a distance of a few feet. We are also aware that radium compound has been proposed for indicating the north point, the

lubbers point and the direction of travel or course; the compound being placed in a tube or as a blob. It has further been proposed to employ a transparent rotary setting scale composed of transparent material and arranged above an annulus having a portion thereof in the line of sight filled with radium compound. i

It has also been proposed to render the markings on dials luminous by erforating the numerals upon a plate beneatli which is a plate having those portions opposite the perforations covered with radio-active material so that the edges of the perforated nu- What we claim as our invention and desire to secure by Letters Patent, is

In a liquid magnetic compass the combination with needles, of a hollow float, hav- 5 ing a dome-shaped central portion, carrying said needles and provided with a pivot pin projecting downward-in said float, a

support for said pivot pin carried by the compass bowl, a compass card carried by said float and having the divisions and fig? 10 ures marked with luminous radium paint,

substantially as described.

FRANK OSBORNE OREAGH-OSBORNE. ARTHUR JOSEPH HUGHES. 

